Various systems are available for mixing particulate materials which can be conveyed to a suitable end point for disposal. For example, U.S. Pat. No. 4,756,626 to Neier discloses a portable "mixer" which can be used to transport and discharge materials broadly characterized as fluent and non-fluent materials. Such materials may include feedlot mixtures which are characterized as relative low density materials and fertilizer mixtures which are characterized as being of somewhat higher density, for example, about 60 lbs./cu.ft. The Neier system includes a pair of elongated side-mounted augers in an auxiliary chamber which are disposed along side a relatively large rotor mounted in a main chamber and having a plurality of elongated rotor bars attached to radial arms extending outwardly from the rotor axle. The two augers and the rotor, rotate about longitudinally extending axes which are parallel to one another. The two augers are provided with curved paddles at opposed ends near a discharge door. The paddles at the end of the upper auger function to move the material down to the lower auger or laterally into the main chamber and the paddles at the reverse end of the lower auger serve to move the materials outwardly through a discharge door or upwardly where they are contacted with the upper auger. In view of the high torque imposed upon the rotor blades, spring-loaded pivoting connections are employed to connect these blades to the radial arms extending outwardly from the axle of the rotor.
U.S. Pat. No. 5,005,495 to Feitel discloses a system for removing volatile organic materials from particulate materials characterized as "sludge" or soil. Such sludge materials are characterized as particulate materials such as soil containing hydrocarbons such as gasoline, fuel oil or kerosine and other such organic materials. The Feitel system incorporates an elongated housing having four forward parallel mounted augers whose flights partially overlap somewhat to provide good mixing and heating of the sludge material within the housing in which the augers are arranged. The augers or "screws" have hollow flights through which a heat exchange medium can be passed as the augers are rotated.
A somewhat similar situation involving the use of parallel mounted screw augers in the handling of waste materials such as sludges and contaminated soils is disclosed in U.S. Pat. No. 5,289,640 to McCabe. Here again, augers are characterized as screw conveyors are mounted in an elongated container for rotation about parallel axis with the auger flights slightly overlapping. As in the case of the systems described previously, the screw conveyors transcend a substantial cross sectional area within the housing in which they are disposed. A discharge port is located at one end of the housing and is equipped with an air lock through which the waste medium may be discharged.
U.S. Pat. No. 5,385,402 to Rumph discloses a system for holding and transporting hazardous waste materials in a manner to provide for thorough mixing of the solid and liquid components of these materials. The Rumph system comprises an elongated tank which can take the form of a tank trailer, truck, railcar or boat which is equipped with an agitation system extending along the length of the tank. The agitation system in Rumph is somewhat similar to the rotor configuration of the aforementioned patent to Neier in that a plurality of elongated blades mounted for rotation with a shaft extending longitudinally of the tank. Like the rotor of Neier, the Rumph agitator transcends a major cross-sectional area of the tank and occupies a substantial vertical dimension of the tank in which it is mounted. Because the elongated blades rotate throughout a substantial cross sectional area of the tank and necessarily incorporate high torque requirements into the system, in order to keep the weight as low as possible, the blades, supports and the radial arms upon which the blades are mounted are made of a relatively lightweight material such as aluminum. The rotary agitation systems in Rumph are driven by suitable internal motors such as hydraulic motors which are powered with hydraulic fluids supplied from an external hydraulic power unit.